Conjugate signaling circuits



July 15 1924. 1,501,103 ESPENSCHIED CONJUGATE SIGNALING CIRCUITS Filed Sept. 26 1919 2 Sheets-Sheet l INVEN TOR.

LE; wise/lied A TTORNEY July 15', 1924. 1,so1,ro3

L. ESPENSCHIED CONJUG'ATE SIGNALING CIRCUITS Filed Sept. 26. 1919' 2 Sheets-Sheet 2 /J. is elzycka'ed ATTORNEY Patented July 15, 1924.

UETED STATES PATENT OFFICE.

LLOYD ESPENSGHIED, OF HOLLIS, NEW YORK, ASSIGNOB T0 AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

CONJUGATE SIGNALING CIRCUITS.

application filed September 26, 1919. Serial No. 826,519.

To all whom it may concern:

Be it known that I, LLOYD EsPENeoH'rEn, residing at Hollis, in the county of Queens and State of New York, have invented certain Improvements in Conjugate Signaling Circuits, of which the following is a specification.

This invention relates to signaling systems, and more particularly to arrangements for associating transmitting and receiving circuits with a common transmission circuit in such a manner as to render the trans mitting and receiving circuits conjugate.

One of the features of the invention consists in the provision of circuit arrangements for relating a transmitting circuit and a receiving circuit to a commontransmissio-n circuit, in such a manner that the transmitting and receiving circuits will be conjugate with respect to each other and will also be conductively connected with the line.

Another object of the invention is to provide an arrangement whereby a transmitting circuit and a receiving circuit may be associated with the common transmission circuit through separate transforming arrangements.

Other and further objects of the invention will appear more fully from the following description when read in connection with the accompanyin drawing, Figures 1, 2, 3, 4 and 5 of which are dia ams illus- 'trating difierent embodiments o the invention.

Referring to Figure 1, ML designates a transmission" line such as a telephone line, which is adapted to be balanced byan artificial'line or network MN. The line ML is connected with the artificial line MN through a pairof bridge circuits 1--2 and 34. The bridge circuit 1-2 contains a transformer or inductance coil arrangement comprising windings 5, 6, 7 and 8 and a receivmg circuit R is connected tothe midpoints' of the windings of the transformer, as indicated. The bridge circuit 34 is similarly provided with a transforming de- Y vlce com rising windings'9, 10, 11 and 12,

to-the-m1dpoints of which a transmitting circuit T is connected. The windings of each transformer or coil unit are disposed upon a common core and so poled as to present maximum impedance for currents flowing circularly around the circuit as in the order 9, 10, 12, 11, and to present a minimum conjugate with respect to each other. For

instance, assuming an impulse in the transmitting circuit T of such character that the junction between the windings 9 and 10 is positive, it will be apparent that since this point is connected through windings 9 and 7 to the junction point of windings 7 and 8 and through windings 10 and 6 to the junction point of windings 5- and 6, both of these junction points will be at the same potential, owing to the fact that the two pairs of windings have the same impedance, (and that the effect of the line ML is balanced by that of the network MN), consequently no current will flow to the receiving circuit R.

The arrangement of Figure 1 is quite satisfactory where onl telephone currents are transmitted over t e line ML, but where Morse currents are also to be transmitted over the line, it may be necessary to sup lement the arrangement of Figure 1 with a ditional apparatus, owing to the difficulty of desi ning coil arrangements which will have simi ar transmission efliclencles and impedtelephone frequencies. In such a case, that of a composited telephone and telegraph circuit, the arrangement of Figure 2 may be preferable. In accordance with this arrangement a supplemental transforming device comprising windings 13, 14, 15 and 16' is provided in the bridge circuit 1--2, the windings of this transforming arrangement offering a relatively large impedance to Morsecurrent variations, but? offering a very small impedance to telephone currents,

owing to the fact that each winding is.

a condenser, as indicated at 21,

,rarrigement the transforming devices may be so esigned that the bridge circuits will offer 24. The bridge circuit 34 is ance effects to currents of both Morse and similar transmission and impedance efi'ects to both voice and Morse currents.

Figure 3 illustrates an arrangement whereby a plurality of transmitting and receiving channels of a carrier system may be superposed u on a commontransmission line, such as by employing transforming arrangements such as above described. In this arrangement the common transmittin and receiving circuits T and R are associated with the midpoints of the transforming devices in the bridge circuits 12 and 34 respectively, in the same manner as in Figure 1 and individual receiving channels R and R are connected wit-h the common receiving circuit R, while individual transmitting channels T T and T are associated with the common circuit T. By providing suitable selective devices such as F F and F in the receiving channels and similar selective devices F' F and F in the transmitting channels a frequency separation between the channels may be obtained. These selective devices may be of.

any well-known type, depending upon the character of transmission. Where telegraph- 1c signals are to be transmitted by means of carrier currents, simple tuned circuits will be satisfactory. Where telephone currents are to be transmitted by carrier waves, however, it is preferable that these selective devices be broad band filters of the type disclosed in the U. S. patents to George A. Campbell, Nos. 1,227,113 and 1,227,11-1. dated May 22, 1917.

While in the arrangement of Figure 3 both transmitting and receiving paths are conductively connected to the bridge circults, in some instances it may be desirable that one of these paths, as for instance the receiving path, should be inductively assoclated with the corresponding bridge circult, wh1le still employing separate transformers for transmitting and' receiving. Such an arrangement is illustrated in Figure 4, in which thetransforming arrangement in the bridge circuit 1-2 comprises three sets of windings, two of which are included in the bridge circuit and the third of whichis included in the common receivmg clrcuit R. In this case, since this conplmg between the circuit R and the bridge circuit 1-2 associates the receiving circuit serially with the bridge circuit, it is necessar to reverse the connections of the bridge at s with the line ML and artificial line N, as indicated. It will now be apparent that if an impulse from the circult T is impressed across the points 29 and 30 points 31 and 32 will be at the same potential and points 33 and 34 will be at ual otentials, although these potentials W 1ll differ from the potentials applied to points 31 and 32, consequentl no current flows through the windingso the transformers in the bridge circuits 12, and consequently no effect is produced upon the receiving path R.

Where it is desired that both the transmitting and receiving paths be associated with the bridge circuits through separate transforming arrangements, while being maintained insulated therefrom as regards the flow of direct currents, three-winding transformers may be provided in both bridge circuits, as illustrated in Figure 5, the third winding of each transformer being included in the corresponding transmitting or receiving circuit such as T and B. As both circuits T and R are now serially related to the corresponding bridge path the terminals of the bridge paths should be nonsymmetrically connected to the line ML and artificial line MN, in the same manner as in Figure 3, instead of being symmetrically connected as described in connection with Figure 4. From this circuit arrangement it will be apparent that if a current flows across in the path T in such a direction as to induce in one of the secondary windings of the transformer an electromotive force such that point 35 is at definite positive potential and point 38 at a definite negative potential, anequal electromotive force will be induced in the other secondary winding, so that the point 36 will be at the same positive potential as the point 35 and the point 37 at the same negative potential as the point38, consequently no current flows through the windings of the transformer in the bridge circuit 12 and the receivmg path R will therefore be unaffected by disturbances in the transmitting path T.

It will be obvious thatthe general principles herein disclosed may be embodied in many other organizations widely different from those illustrated, without departing from the spirit of the invention as defined in the following claims:

What is claimed is: a

1. In a signaling system, a transmission circuit, an artificial line for'balancing said circuit, a transmitting path. a receiving path, and a pair of bridge paths, each bridge path having three connections only, two connections of each bridge path being so arranged as to connect the bridge paths n parallel between said transmission circuit and artificial line, the third connection of one of said bridge paths connecting said transmitting path thereto independently of its other two connections, and the third connection of the other bridge path connecting said receiving path thereto independently of its other two connections, the connections bein such that said receiving and transmittmg paths will be conjugate with respect to each other. I

2. In a signalin system, a transmission circuit, an artificia line for balancing said circuit, a transmitting path, a receiving nections, and the third connection of the other bridge path connecting said receiving path thereto independently of its other two connections.

3. 'In a signaling system, a transmission circuit, an artificial line for balancing said circuit, a pairof'bridge paths connected in parallel between said transmission circuit and artificial line, reactance coil arrangements included in said bridge paths, a trans mitting path conductively connected only to one of said bridge paths independently of its connection to the transmission circuit and artificial line, and a receiving path conductively connected onlyto the other bridge path independently of its connection to the transmission circuit and artificial line.

l. In a signaling system, a transmission circuit, an artificial line for-balancing said circuit, a transmitting path, a receiving path, a pair of bridge paths, reactance devices in said bridge paths, and each of said bridge paths having three connections only, two of the connections of each of said paths being so arranged as to connect said bridge paths in parallel between said transmission c rcuit and artificial line, the third connection of one of said paths connecting said transmitting path thereto independently of its other two connections, and the third connection of the other bridge path connecting said receiving path thereto independently of its other two connections, the third connec- 1 points of the'windings in one bridge path,

' tion of one of'said bridge paths being conductive...

5. In a signaling system, a transmission circuit, an artificial line for balancing said circuit, a pair of bridge paths interconnecting said transmission circuit and artificial line, inductive windings in each bridge path, a transmitting path connected to the midand a receiving path connected to the mid- POlIfilS of the windings in the other bridge pat m 6. In a signaling system, a transmission circuit, an artificial line for balancing said circuit, a pair of bridge paths interconnecting said transmission circuit and artificial line, inductive windings in each bridge path, a transmitting path connected to the midpoints of the windings in one bridge path, a receiving path connected to the midpoints of the windings in the other bridge path, and a-plurality of signaling channels superposed upon each of said transmitting and receiving paths.

7 In a signaling system, a transmission circuit, an artificial line-for balancing said circuit, a transmitting path, a receiving path, a pair of bridge paths, inductive Windings in each of said bridge paths, having three connections only, two connections of 'being a conductive connection to the midpoints of the windings therein. 8. In-a signaling system, a transmission circuit, an artificial line for balancing said circuit, a pair of bridge paths interconnecting said transmission circuit and artificial line, inductive windings in each of said bridge paths, a transmitting path associated with one of said bridge paths, a receiving path associated withthe other bridge path,

oneof said transmitting and receiving paths being conductively connected, to the midpoints of the windings in the correspond ng bridge path, and a plurality of signaling channels associated with each of said transmitting and receiving paths,

In testimony whereof I have signed my name to this specification this 25th September, 1919.

LLOYD ESPENSGHIED.

day of 

